On the Operational Orthogonality of Languages. Daley, M., Domaratzki, M., & Salomaa, K. Journal of Computer and System Science, 2009.
bibtex   
@article{oporth09,
	Author = {Daley, Mark and Domaratzki, Michael and Salomaa, Kai},
	Date-Added = {2010-02-08 13:36:33 -0500},
	Date-Modified = {2010-02-08 13:37:45 -0500},
	Journal = {Journal of Computer and System Science},
	Title = {On the Operational Orthogonality of Languages},
	Volume = {to appear},
	Year = {2009}}

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